A problem has existed in providing a simple and inexpensive drum lifting device which can be quickly attached to a crane, fork truck, or the like for lifting shipping drums. Steel shipping drums or barrels are used for shipping commodities such as chemicals, paints, janitorial supplies, and food products. One of the more commonly used drums has a capacity of fifty-five gallons. One man is not able to move such large shipping drums without the aid of a tool such as a drum lifter or the like.
The drum lifter must be simple to use, inexpensive, and perform at least two functions. The drum lifting device must keep the drum relatively upright when it is lifted off the ground for various reasons such as keeping the contents of the drum from shifting or permitting easier placement of the drum on an elevated storage area. The drum lifter also must be self-energizing or capable of handling various drum weights with gripping strengths proportional to the weights of the drums. The holding or gripping force necessary to suspend a twenty-five-gallon drum containing paint, for example, is not sufficient to suspend a fifty-five gallon drum containing a like material. As the drum gets heavier, the same drum lifter must be capable of holding the additional weight.
An additional problem with some prior drum lifters such as shown in U.S. Pat. No. 3,333,883 is that the gripping force tends to be concentrated directly on the upper drum chime. This is detrimental for an open-head drum that has a locking ring to hold a removable top head because the gripping force could pull the locking ring off the drum.